Sorry for the delay in replying ... I've just finished a morning's admin ...and have a bit of time over lunch to respond properly now.
MrsGatsby99 thank you very much; I am very familiar with Flylady and found the system (pre-pandemic) to work well with the everyday housekeeping tasks eg tidying, cleaning, shopping, cooking, laundry etc but not so much with the decluttering tbh. There is always so much everyday stuff going on!
Having said that, I find The Organised Mum Method better when everyone is working from home, but again, not with decluttering! My house isn't overly- cluttery btw, but things have built up over the years ... . And although other people in the house accumulate "stuff" they don't take it upon themselves to get rid.
It is literally down to me to go through every draw, cupboard and bag. Previous attempts by other members of the family to declutter have unfortunately resulted in random likes of "unresolved" piles of "stuff" dotted about on any spare surface.
I will look at The Secret Slob on You Tube thank you!
That is very helpful Tenam thank you. I will definitely be adopting the drawer-by-drawer room-by-room approach for the reasons you have described! How long did it take you to sort your house completely if you don't mind me asking? And do you have days when you don't do any cleaning at all, other than "maintenance tasks" I mean? That's a great tip about the stairs counting as one room btw! Thank you!
I don't have as much stuff as your (well organised! 
) mum ( I am impressed by the eighteen slotted spoons!) but there are areas (cellars, attics) which have accumulated heaven knows what.
And times move on don't they? The things you thought were vital to keep initially (baby clothes?) you may think of differently as the years roll on ... . Same with some children's books, school books, camping gear, sports equipment and I definitely have too much bed-linen etc etc. Its not too bad as I have always done six monthly chuck outs of clothes and toys but that has waned a bit through the teenage years.
Happily Gassylady we have , as of 1st Jan, put a moratorium on anything new coming in to the house before it is decluttered and back in to a good state of order! This rule is designed to speed up the process and encourage everyone's involvement ...we'll see how it goes anyway. But we've all agreed that if we are tempted to buy anything new that's not absolutely essential, then we will divert that urge and put a note or three in a glass jar (or do the equivalent on-line) and make a donation to a local charity that's important to us instead! . We've signed a contract and everything and stuck it on the fridge! I will have a look at the decluttering one thing a day threads, thank you!
I think I need to do an initial declutter, thank you tinkywinkyshandbag but you and other posters have reminded me that I need to be realistic about this task and get some help with it! You've also "given me permission" in my head to call in cleaning help, ridiculous though that sounds!
Thank you for your good wishes BasiliskStare and gosh yes yes to I think part of the thing about having a very big house - is there are just so many places to stash stuff and ignore that is so true! I am probably underestimating how much stuff I have stashed away!
I had to laugh about the fish kettle and margarita glasses though! (Signs of a life well lived?! ) We have the former but not the latter!) The books are a very difficult thing for me. We have hundreds and hundreds. It is going to be a slow process I think ...but the Internet is a game changer in terms of reference books ...and I also think I may enjoy it eventually! I will certainly be far less stressed when my house is under control!
And I agree that one can get too fixated on method rather then the actual doing! And I need to be realistic about the time it will take after 20 years plus of family life.
I hope I haven't missed anyone!
Thank you again for all of the helpfull tips and encouragement; it is much appreciated!